This invention relates to electrical connectors of the type having a connector body and a plurality of posts extending out of one side of the connector body for mounting to a circuit board. In particular, this invention relates to an improved retention feature for such electrical connectors for temporarily holding the electrical connector in place on a printed circuit board prior to soldering.
U.S. Pat. No. 4,847,588 discloses an electrical connector with a retention feature in which the posts of the connector are offset in the form of a crimp to create frictional forces against the side wall of the through hole of the circuit board onto which the electrical connector is mounted. The disclosed retention feature relies entirely on friction, and does not provide any latching force tending to secure the electrical connector in position on the circuit board.
In another type of retention feature for electrical connectors individual pins of the connector are formed to create a latching force against the bottom surface of the circuit board on which the electrical connector is mounted. See for example U.S. Pat. No. 3,524,108 and Japanese UM Publication No. 57-86270. Such below the board retention features can provide an audible click when the connector is seated on the circuit board, and some users regard below the board retention features as more stable.
When below the board retention features are applied to relatively stiff posts such as posts having a cross sectional dimension of 0.025 by 0.025 inches, problems have been encountered. These problems relate to the fact that the through hole geometry of the circuit board varies within a range of tolerances, and the retention feature must function properly throughout this range. In a below the board retention feature the corners of the post latch against the corner of the through hole. In the past, there has been a tendency with relatively thick and inflexible posts for the retention feature to damage the tin plating of the through hole at the corner of engagement with the post, at least when the through hole is near one edge of the tolerance range. This problem has in the past limited the use of below the board retention features with stiff posts.